This will allow to use gpio for chip select with no modification in the
driver binding
When use the ncs-gpio, the gpio number will be passed via the controller_data
and the number of chip select will automatically increased.
When a spi master have only gpio chip select and is probe via dt check the
number of chip select only when adding slave.
Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagn...@jcrosoft.com>
Cc: devicetree-disc...@lists.ozlabs.org
Cc: spi-devel-general@lists.sourceforge.net
---
Documentation/devicetree/bindings/spi/spi-bus.txt | 9 ++++++-
drivers/of/of_spi.c | 27 ++++++++++++++------
drivers/spi/spi.c | 2 +-
3 files changed, 28 insertions(+), 10 deletions(-)
diff --git a/Documentation/devicetree/bindings/spi/spi-bus.txt
b/Documentation/devicetree/bindings/spi/spi-bus.txt
index e782add..1dccf35 100644
--- a/Documentation/devicetree/bindings/spi/spi-bus.txt
+++ b/Documentation/devicetree/bindings/spi/spi-bus.txt
@@ -21,9 +21,16 @@ assumption that board specific platform code will be used to
manage
chip selects. Individual drivers can define additional properties to
support describing the chip select layout.
+If a gpio a specified to the SPI slave and no hardware chip select is present
+the reg property #address-cells and #size-cells are not needed.
+
+When use the ncs-gpio the gpio number will be passed via the controller_data
+and the number of chip select will automatically increased.
+
SPI slave nodes must be children of the SPI master node and can
contain the following properties.
-- reg - (required) chip select address of device.
+- reg - (required if no ncs-gpio) chip select address of device.
+- ncs-gpio - (required if no reg) chip select gpio of device.
- compatible - (required) name of SPI device following generic names
recommended practice
- spi-max-frequency - (required) Maximum SPI clocking speed of device in Hz
diff --git a/drivers/of/of_spi.c b/drivers/of/of_spi.c
index 6dbc074..0d41407 100644
--- a/drivers/of/of_spi.c
+++ b/drivers/of/of_spi.c
@@ -12,6 +12,7 @@
#include <linux/spi/spi.h>
#include <linux/of_irq.h>
#include <linux/of_spi.h>
+#include <linux/of_gpio.h>
/**
* of_register_spi_devices - Register child devices onto the SPI bus
@@ -27,6 +28,7 @@ void of_register_spi_devices(struct spi_master *master)
const __be32 *prop;
int rc;
int len;
+ int ncs_pin;
if (!master->dev.of_node)
return;
@@ -50,15 +52,24 @@ void of_register_spi_devices(struct spi_master *master)
continue;
}
- /* Device address */
- prop = of_get_property(nc, "reg", &len);
- if (!prop || len < sizeof(*prop)) {
- dev_err(&master->dev, "%s has no 'reg' property\n",
- nc->full_name);
- spi_dev_put(spi);
- continue;
+ /* ncs gpio */
+ ncs_pin = of_get_named_gpio(nc, "ncs-gpio", 0);
+
+ if (gpio_is_valid(ncs_pin)) {
+ spi->controller_data = (void *)ncs_pin;
+ spi->chip_select = master->num_chipselect;
+ master->num_chipselect++;
+ } else {
+ /* Device address */
+ prop = of_get_property(nc, "reg", &len);
+ if (!prop || len < sizeof(*prop)) {
+ dev_err(&master->dev, "%s has no 'reg'
property\n",
+ nc->full_name);
+ spi_dev_put(spi);
+ continue;
+ }
+ spi->chip_select = be32_to_cpup(prop);
}
- spi->chip_select = be32_to_cpup(prop);
/* Mode (clock phase/polarity/etc.) */
if (of_find_property(nc, "spi-cpha", NULL))
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index b2ccdea..ccd1a6f 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -595,7 +595,7 @@ int spi_register_master(struct spi_master *master)
/* even if it's just one always-selected device, there must
* be at least one chipselect
*/
- if (master->num_chipselect == 0)
+ if (!master->dev.of_node && master->num_chipselect == 0)
return -EINVAL;
/* convention: dynamically assigned bus IDs count down from the max */
--
1.7.7
------------------------------------------------------------------------------
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